4 Months Pregnant: Symptoms, Baby (& Belly) Size and Development

Updated: November 24, 2021
Here we look at the second trimester of your pregnancy and take you through the common signs and symptoms as well as your baby's size and development and your 4 month pregnant belly.
What to Expect in Your Fourth Month of Pregnancy
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Welcome to the second trimester of your pregnancy! The start of month four indicates the end of your first trimester, and you are now entering what many women refer to as the honeymoon period. Your energy is up, and your meals are staying down. You and your baby are headed into a period of rapid growth. It’s time to hang on and enjoy the ride!

This article will cover second-semester pregnancy symptoms, fetal development, and all the ins and outs of your fourth month of pregnancy.

Four Months Pregnant Signs and Symptoms Checklist

  • Treat yourself to a special day out.
  • Begin keeping a food log.
  • If you don't have one, shop for a crib that meets current safety standards.
  • Create a prenatal exercise routine.
  • Start discussing baby names with your partner.
  • Start a registry checklist or begin browsing baby stores for ideas
  • Decide if you want to know your baby’s gender before birth

Size of Your Baby at Four Months Pregnant

Snoozing, stretching, swallowing, and even thumb-sucking are all things your baby can do now! They are testing out their new reflexes and abilities even if you can’t feel the movements yet. In addition, they are losing their top-heavy look as your baby’s head and length begin to even out.

The size of your baby at four months pregnant is roughly 6 inches, and they weigh approximately 6 ounces.Your baby’s nervous system is beginning to develop, and their facial features such as their eyelids, eyebrows, hair, and eyelashes are all developing.

Around 16 weeks of pregnancy, your baby will develop a fine layer of hair over their body called lanugo. Lanugo develops to help a waxy substance called vernix to adhere to your baby’s skin. Together the lanugo and vernix protect your baby’s skin from the amniotic fluid they are floating around in. The amniotic sac is what protects your baby as they develop. The term “water breaking” refers to when the amniotic sac bursts.

Pregnancy Symptoms in Month Four (16 Weeks)

During your fourth month, most pregnant women notice an uptick in energy, and symptoms such as morning sickness and fatigue fade away. On the flip side, however, you may notice heartburn and constipation. Additionally, your breast may begin to become tender or sore, and the areolas may darken. Due to the increased blood flow your body is managing, you may also suffer from nosebleeds, bleeding gums, nasal congestion, and lightheadedness.

Pregnancy Heartburn

Heartburn may start to become a persistent problem in your second trimester as your uterus crowds your stomach and the smooth muscles of your digestive tract remain relaxed from the hormone progesterone. Some tips for putting out the fire include:

  • Avoid greasy, fatty, and spicy foods.
  • Stay away from alcohol and caffeinated drinks (e.g., cola, tea, coffee); these may relax the valve between the stomach and the esophagus and exacerbate heartburn.
  • Eat smaller, more frequent meals instead of three large ones.
  • Drink plenty of water between meals to reduce stomach acid.
  • Don't eat just before you go to bed or lay down to rest.
  • Pile a few extra pillows on the bed to assist gravity in easing heartburn while you sleep.

Varicose Veins and Stretch Marks

Varicose veins and stretch marks may also begin to form in your fourth month. Despite claims made by endless ointments and creams, there is nothing you can do to prevent stretch marks, but gradually gaining weight may decrease their chances of developing.

Varicose veins aren’t usually harmful, but they can be sore and feel painful at times. Your veins are blood vessels that carry blood throughout your body — increased blood flow that occurs while pregnant can contribute to the twisting and swelling of your veins.

Like stretch marks, there isn’t much you can do to prevent them, but walking and gentle exercise can relieve some of the discomforts they bring.

Round Ligament Pain

Round ligament pain is a common complaint in the second trimester. It is usually felt as a sharp stab or jab of abdominal pain on your right side. Your round ligaments are located in your pelvis. As your uterus grows, they lengthen and thicken to support the weight.

You are most likely to experience round ligament pain when you change positions, sit up quickly, like getting out of bed or a chair, or getting up from a height distance such as the bathtub or the floor.

Warm baths, a walk, and stretches can all relieve the pain. If your doctor approves the use, you can also take acetaminophen for the pain.

Additional Pregnancy Symptoms During the Second Trimester

Other second-trimester pregnancy symptoms you may start or continue to experience this month include the following. Use this list as a guide to discuss relief options with your healthcare provider:

  • Hemorrhoids
  • Nausea
  • Fatigue
  • Frequent urination
  • Excess mucus and saliva
  • Increase in vaginal discharge
  • Mild shortness of breath
  • Lightheadedness or dizziness
  • Gas and/or constipation
  • Skin and hair changes
  • Feeling warm or easily overheated

Size of Baby Bump at Four Months and Other Body Changes

Baby Bump

If you weren't showing last month, chances are you will have a definite baby bump by the end of this month. Your uterus is about the size of a head of cabbage, and its top lies just below your belly button.

Your appetite may start to pick up this month, especially if you've been too sick to enjoy a good meal until now, and you may begin to experience some specific cravings.

You will gain about 60 percent of your total pregnancy weight (about eleven to fifteen pounds) in this trimester. Remember, weight gain is normal and expected; however, discuss it with your OB/GYN if you have concerns about how much or how little weight you are gaining.

As your little one continues to grow and the shape of your body changes, it may be time to purchase some maternity clothes. Maternity clothes can be costly, so try looking at consignment shops and invest in a few solid basics like a nice pair of jeans, dress slacks, and some simple dresses you can dress up with jewelry or scarves.

The fourth month is when some women feel their baby move for the first time, this is called quickening. It usually happens between 16 and 25 weeks, but some women feel it as early as 13 weeks.

Pregnancy Emotions and Mood Changes at Four Months

You're hitting your stride as the dizziness and uncertainties of the first three months fade away, and the discomforts of late pregnancy still lie relatively far ahead. Feeling better and having more energy, you may be ready to conquer the world (or at least the nursery). And, once you feel those first fluttery movements, the reality of becoming a parent has probably hit. Pregnancy hormones likely have your emotions all over the place, and you may feel the need to nest and prepare for the baby’s arrival.

The palpable presence of your child may trigger a series of mothering emotions-protectiveness, nurturing, nesting-and complete and total impatience with anyone who poses a potential threat to the well-being of you and your child.

What to Expect at a Four-Month Checkup

The second trimester is typically an easygoing time for most moms; however, there are some situations, regardless of how far along you are, warrant a call to the doctor.

  • Spotting
  • Heavy bleeding
  • Severe back or abdominal pain
  • High fever (102 or higher)
  • Pain with urination
  • Vision changes or dizziness
  • Watery vaginal discharge (as if your amniotic sac has broken)
  • Severe or persistent headache
  • Persistent vomiting or diarrhea

There's lots to keep track of and lots to do in your second trimester. Keep it all straight with our Second Trimester To-Do List.

And check out our featured video on the general symptoms of pregnancy.

Month Five of Your Pregnancy